The present invention relates to a printer for use with a ribbon cassette having a rotatable supply core around which an inked ribbon is wound and a rotatable take-up core onto which the inked ribbon is taken up, for thermally transferring solid ink on the inked ribbon onto a sheet.
In a printer of the aforementioned type, the inked ribbon cannot be reused, because the ink on the inked ribbon is thermally transferred onto the sheet during the printing operation thereby resulting in increasing the overall operating cost of the printer.
In order to solve the above problem, it has been proposed to divide the ink on the inked ribbon into at least a first and a second track extending longitudinally of the ribbon in parallel to each other and to use the second track after the first track has been used. Such a proposal is disclosed in, for example, Japanese Utility Model Laid-Open No. 58-194042 and Japanese Patent Laid-Open No. 57-47685. However, in the above noted proposals, the inked ribbon, fed from the supply core to the take-up core, tends to be shifted perpendicularly in the longitudinal direction of the inked ribbon relative to a printing head facing the inked ribbon. Due to the lateral shifting of the inked ribbon, a new problem occurs in that the ink ribbon approaches an upper inner wall surface or a lower inner wall surface of a casing of the ribbon cassette as the inked ribbon is taken up onto the take-up core and, finally, the inked ribbon contacts the upper or the lower inner wall surface. The contact of the inked ribbon being taken up onto the take-up core with the upper or lower inner wall surface makes it impossible to take up the inked ribbon properly onto the take-up core. Further, in case the inked ribbon has at least two tracks, the allowance of the lateral shifting of the ribbon relative to the printing head is smaller than the case in which the central area in the width of the inked ribbon is used in the printing operation. Thus, when the inked ribbon is shifted laterally with respect to the printing head even by a small amount, it will be shifted out of the printing area on the printing head or, when the second track on the inked ribbon is used in the printing operation, the printing area on the printing head will be positioned on the first track from which the ink has already been stripped out thereby characters.
An object of the present invention is to provide a printer which makes it possible to prevent the inked ribbon from shifting perpendicularly to the longitudinal direction of the inked ribbon at the printing head where the inked ribbon faces thereagainst.
Another object of the present invention is to provide a combination of a ribbon cassette and a printer wherein the ink ribbon which has once been used in the printing operation can again be used.
In accordance with the present invention, a printer for use with a ribbon cassette is provided which includes a rotatable supply core having an inked ribbon wound therearound and a rotatable take up core for taking up the inked ribbon, for thermally transferring solid ink on the ink ribbon to a sheet, with the printer including an elongated platen extending substantially perpendicular to a direction of movement of the sheet upon a starting of a new line, and a carriage reciprocated longitudinally of the platen, with the ribbon cassette loaded on the carriage for movement therewith.
A printing head is mounted on the carriage for movement therewith for applying thermal energy for the thermal transfer of the inked ribbon, with the printing head being movable between the first position remote from the platen and a second position where a portion of the inked ribbon extending between the supply and take up cores of the ribbon cassette is urged by the printing head against the sheet on the platen to thereby thermally transfer the ink within an area of the inked ribbon portion to the sheet. An area of the ink ribbon portion has a width which is at most equal to one half of a width of the inked ribbon. The platen has a surface facing the printing head through the inked ribbon and sheet when the printing head occupies a second position, with the surface of the platen being substantially planar over an extent within which the printing head is reciprocated.
According to further features of the present invention, a ribbon cassette and printer for thermally transferring solid ink on an inked ribbon within a ribbon cassette to a sheet is provided wherein the ribbon cassette includes a rotatable supply core having an inked ribbon wound therearound and a rotatable take up core for taking up the inked ribbon. The printer includes an elongated platen which extends substantially perpendicular to a direction of movement of the sheet upon starting of a new line, and a carriage reciprocated longitudinally of the platen, with the ribbon cassette capable of being loaded on the carriage for movement therewith. A printing head is mounted on the carriage for movement therewith, with the printing head being movable between a first position remote from the platen and a second position. A portion of the linked ribbon extending between the supply and take up cores of the ribbon cassette, is urged by the printing head against the sheet on the platen to thermally transfer the ink within the area of the linked ribbon portion to the sheet. An area of the linked ribbon portion has a width being at most equal to one half of a width of the inked ribbon. A mechanism is provided for rotatably driving the take up core of the ribbon cassette to impart a taking-up tension to the linked ribbon portion. Means are mounted on either one of the carriage of the printer or the ribbon cassette and are operative in response to a change in diameter of the inked ribbon wound around the supply core for imparting a variable back tension, opposite to the take-up tension, to the inked ribbon so as to constantly satisfy the following inequality, with the back tension being variable so as to be reduced in accordance with the reduction in the diameter of the inked ribbon wound around the supply core: EQU fo/fi&lt;.alpha.,
where .alpha. is a constant,
fo is a take-up tension, and PA1 fi is a variable back tension. PA1 .alpha. is a constant, PA1 fo is a take up tension, and PA1 fi is a variable back tension.
In accordance with further advantageous features of the present invention, a ribbon cassette for a printer is provided which includes a casing, a supply core rotatably disposed within the casing, with the supply core having an inked ribbon wound therearound. A take up core is rotatably disposed within the casing for taking up the inked ribbon with a taking up tension upon operation of the printer. Means are disposed within the casing for imparting, in response to a change in diameter of the inked ribbon wound around the supply core, a variable back tension opposite to the take up tension, to a portion of the inked ribbon extending between the supply and take up cores so as to constantly satisfy the following inequality, with the back tension being variable so as to be reduced in accordance with a reduction in the diameter of the inked ribbon wound around the supply core, EQU fo/fi&lt;.alpha.,
where:
According to the present invention an inked ribbon unit and a printer for thermally transferred solid ink on an inked ribbon of the inked ribbon unit to a sheet is provided wherein the inked ribbon unit includes a rotatable supply core having the inked ribbon wound thereon and a rotatable take up core for taking up the inked ribbon. The printer includes an elongated platen extending substantially perpendicular to a direction of movement of the sheet upon a starting of a new line, with movable means being adapted to be reciprocated longitudinally of the platen. A printing head is mounted on the movable means for movement therewith, with the printing head being movable between a first position remote from the platen and a second position where a portion of the inked ribbon, extending between the supply and take up cores of the inked ribbon unit, is urged by the printing head against the sheet on the platen to thermally transfer solid ink on the inked ribbon portion to the sheet. Detecting means are provided for detecting whether or not the ink exists on the inked ribbon to respectively generate a first signal when the ink exists on the inked ribbon and a second signal when the ink at least partially does not exist on the inked ribbon. Control means, operative in response to the first signal from the detecting means, control the printer so as to allow the printer to perform a printing operation, and are operative in response to the second signal from the detecting means for controlling the printer so as to prevent a printing operation. Enabling means are provided for enabling the detecting means to generate the first signal regardless of whether the ink exists on the inked ribbon.
According to the present invention, a ribbon cassette and printer for thermally transferring solid ink on an inked ribbon within the ribbon cassette to a sheet is provided wherein the ribbon cassette includes a rotatable supply core having the inked ribbon wound thereon and a rotatable take up core for taking up the inked ribbon. The printer includes an elongated platen extending substantially perpendicular to a direction of movement of a sheet upon starting a new line, and a carriage reciprocated longitudinally of the platen. The ribbon cassette is loaded on the carriage for movement therewith, and a printing head is mounted on the carriage for movement therewith. The printing head is movable between a first position remote from the platen and a second position where a portion of the inked ribbon, extending between the supply and take up cores of the ribbon cassette, is urged by the printing head against the sheet on the platen to thermally transfer the ink within the area of the inked ribbon portion to the sheet. Detecting means detect whether or not ink exists on the inked ribbon to respectively generate a first signal when the ink exists on the inked ribbon and a second signal when the ink at least partially does not exist on the inked ribbon. Control means, operative in response to the first signal from the detecting means, control the printer so as to allow the printer to perform its printing operation and, in response to the second signal from the detecting means, controls the printer so as to prevent a printing operation. Further means enable the detecting means to generate the first signal regardless of whether or not the ink exists on the inked ribbon.